#define __STDC_CONSTANT_MACROS
#ifdef _WIN32
//Windows
extern "C"
{
#include "libavformat/avformat.h"
#include "libavutil/mathematics.h"
#include "libavutil/time.h"
}
#else
//Linux...
#ifdef __cplusplus
extern "C"
{
#endif
#include <libavformat/avformat.h>
#include <libavutil/mathematics.h>
#include <libavutil/time.h>
#ifdef __cplusplus
};
#endif
#endif

int main(int argc, char* argv[])
{
    AVOutputFormat *ofmt = NULL;
    AVFormatContext *ifmt_ctx = NULL, *ofmt_ctx = NULL;
    AVPacket pkt;
    const char *in_filename, *out_filename;
    int ret, i;
    int videoindex=-1;
    int frame_index=0;
    int64_t start_time=0;
    int64_t pts=0;
    int64_t dts=0;

    in_filename = "rtsp地址";

    out_filename= "推送rtmp地址";
    //out_filename = "rtp://233.233.233.233:6666";//输出 URL（Output URL）[UDP]

   // 初始化ffmpeg
    av_register_all();
    // 初始化网络库
    avformat_network_init();
    // 初始化输入
    if ((ret = avformat_open_input(&ifmt_ctx, in_filename, 0, 0)) < 0) {
        printf( "Could not open input file.");
        goto end;
    }
    if ((ret = avformat_find_stream_info(ifmt_ctx, 0)) < 0) {
        printf( "Failed to retrieve input stream information");
        goto end;
    }
    for(i=0; i<ifmt_ctx->nb_streams; i++)
        if(ifmt_ctx->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO){
            videoindex=i;
            break;
        }

    // 打印流媒体信息
    av_dump_format(ifmt_ctx, 0, in_filename, 0);
    // 输出流
    avformat_alloc_output_context2(&ofmt_ctx, NULL, "flv", out_filename); //RTMP
    //avformat_alloc_output_context2(&ofmt_ctx, NULL, "mpegts", out_filename);//UDP
    if (!ofmt_ctx) {
        printf( "Could not create output context\n");
        ret = AVERROR_UNKNOWN;
        goto end;
    }
    ofmt = ofmt_ctx->oformat;
    printf("ifmt_ctx->nb_streams=%d \n" , ifmt_ctx->nb_streams);

    for (i = 0; i < ifmt_ctx->nb_streams; i++) {
        //Create output AVStream according to input AVStream
        AVStream *in_stream = ifmt_ctx->streams[i];
        AVStream *out_stream = avformat_new_stream(ofmt_ctx, in_stream->codec->codec);
        if (!out_stream) {
            printf( "Failed allocating output stream\n");
            ret = AVERROR_UNKNOWN;
            goto end;
        }
        //Copy the settings of AVCodecContext
        ret = avcodec_copy_context(out_stream->codec, in_stream->codec);
        if (ret < 0) {
            printf( "Failed to copy context from input to output stream codec context\n");
            goto end;
        }
        out_stream->codec->codec_tag = 0;
        if (ofmt_ctx->oformat->flags & AVFMT_GLOBALHEADER)
            out_stream->codec->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
    }
    // 打印输出流信息
    av_dump_format(ofmt_ctx, 0, out_filename, 1);

    // 使用avio_open 打开输出
    if (!(ofmt->flags & AVFMT_NOFILE)) {
        ret = avio_open(&ofmt_ctx->pb, out_filename, AVIO_FLAG_WRITE);
        if (ret < 0) {
            printf( "Could not open output URL '%s'", out_filename);
            goto end;
        }
    }
    // 输出写文件头
    ret = avformat_write_header(ofmt_ctx, NULL);
    if (ret < 0) {
        printf( "Error occurred when opening output URL\n");
        goto end;
    }
    start_time=av_gettime();

    while (1) {
        printf("before pts=%i dts=%i\n" , pkt.pts,pkt.dts);
        printf("pkt.stream_index=%i\n" , pkt.stream_index);
        AVStream *in_stream, *out_stream;
        //获取一帧
        ret = av_read_frame(ifmt_ctx, &pkt);
        if (ret < 0)
            break;
        // 如果没有PTS ， 例如H.264裸流
        //更简单的处理就用 PTSpkt.pts==AV_NOPTS_VALUE
        if(pkt.pts==AV_NOPTS_VALUE){
            //Write PTS
            AVRational time_base1=ifmt_ctx->streams[videoindex]->time_base;
            //Duration between 2 frames (us)
            int64_t calc_duration=(double)AV_TIME_BASE/av_q2d(ifmt_ctx->streams[videoindex]->r_frame_rate);
            //计算 pts的公式
            pkt.pts=(double)(frame_index*calc_duration)/(double)(av_q2d(time_base1)*AV_TIME_BASE);
            pkt.dts=pkt.pts;
            pkt.duration=(double)calc_duration/(double)(av_q2d(time_base1)*AV_TIME_BASE);
        }
        //Important:Delay
        if(pkt.stream_index==videoindex){
            AVRational time_base=ifmt_ctx->streams[videoindex]->time_base;
            AVRational time_base_q={1,AV_TIME_BASE};
            int64_t pts_time = av_rescale_q(pkt.dts, time_base, time_base_q);
            int64_t now_time = av_gettime() - start_time;
            if (pts_time > now_time)
                av_usleep(pts_time - now_time);
        }
        in_stream = ifmt_ctx->streams[pkt.stream_index];
        out_stream = ofmt_ctx->streams[pkt.stream_index];

        // 复制包
        if (pts == 0)
        {
            pts = pkt.pts;
            dts = pkt.dts;
        }
        else
        {
            pkt.pts += pts;
            pkt.dts += dts;
        }

        pkt.pts = av_rescale_q_rnd(pkt.pts, in_stream->time_base, out_stream->time_base, (AVRounding)(AV_ROUND_NEAR_INF|AV_ROUND_PASS_MINMAX));
        pkt.dts = av_rescale_q_rnd(pkt.dts, in_stream->time_base, out_stream->time_base, (AVRounding)(AV_ROUND_NEAR_INF|AV_ROUND_PASS_MINMAX));
        pkt.duration = av_rescale_q(pkt.duration, in_stream->time_base, out_stream->time_base);

        pkt.pos = -1;
        // 打印log
        if(pkt.stream_index==videoindex){
            printf("Send %8d video frames to output URL\n",frame_index);
            frame_index++;
        }

        //ret = av_write_frame(ofmt_ctx, &pkt);
        printf("after pts=%i dts=%i\n" , pkt.pts,pkt.dts);
        ret = av_interleaved_write_frame(ofmt_ctx, &pkt);
        if (ret < 0) {
            printf( "Error muxing packet %d \n",ret);
            break;
        }
        av_free_packet(&pkt);
    }
    //Write file trailer
    av_write_trailer(ofmt_ctx);
end:
    avformat_close_input(&ifmt_ctx);
    /* close output */
    if (ofmt_ctx && !(ofmt->flags & AVFMT_NOFILE))
        avio_close(ofmt_ctx->pb);
    avformat_free_context(ofmt_ctx);
    if (ret < 0 && ret != AVERROR_EOF) {
        printf( "Error occurred.\n");
        return -1;
    }
    return 0;
}
